地球科学と気候変動ジャーナル

抽象的な

Evidence of Northward Limit of Sea Level Transgression in and around Central Part of Bangladesh during Holocene

Rashid T, Saha SK and Hassan Z

The study deals with reconstruction of paleoenvironment of the central part of Dhaka in order to explore the northward limit of sea level transgression in Bangladesh. The study area is located at Sutrapur village on the left bank of Turag River in the Pleistocene Madhupur tract of Dhaka city. Lithostratigraphic analysis along with pollen and diatom analyses were performed. The lithostatigraphic records at Shutrapur site show that the Holocene fresh water deposit overlies the Madhupur Clay and Sand Formation. The site shows evidence of weathering in Madhupur Clay and Sand Formation which infers that the tract might have eroded and exposed for some period and weathering acted upon the tract during that time. The pollen and diatom results reveal that the dissect valley filled with Holocene fresh water lentic deposits during the late Holocene period. In addition, the present study found that the Shutrapur site could not receive marine water while the Chatbari site (23 km south from Shutrapur site) experienced with marine transgression approximately 5500 cal yrs BP. It infers that the marine limit persisted at or around the Chatbari site and marine influence could not reach at Shutrapur site.